Outline

The quick diagnosis of Burkitt's lymphoma (BL) and its clear-cut delimitation from diffuse large B-cell lymphoma (DLBCL) is of great clinical importance as treatment strategies for these two diseases differ markedly. As these two lymphomas are difficult to distinguish using the current WHO classification, we studied thirty-nine cases of highly proliferative blastic B-cell lymphoma (HPBCL) to establish a practical differential-diagnostic algorithm. Characteristics set for BL were a typical morphology, a mature B-cell phenotype of CD10+, Bcl-6 + and Bcl-2 - tumour cells, a proliferation rate of >95%, and the presence of C-MYC rearrangements in the absence of t(14;18). Congruency of all these features was found in only 5/39 cases, whereas the majority of tumours revealed mosaic compositions. We then followed a pragmatic stepwise approach for a classification algorithm that includes the assessment of C-MYC status to stratify HPBCL into four diagnostic categories (DC), namely DC1 (5/39, 12.8%): “classical BL”, DC2 (11/39, 28.2%): “atypical BL”, DC3 (9/39, 23.1%): “C-MYC+ DLBCL ”, and DC4 (14/39, 35.9%): “C-MYC- HPBCL”. This proposal may serve as a robust and objective operational basis for therapeutic decisions for HPBCL within one week. However, the prognostic relevance of our classifier needs to be evaluated in a prospective clinical trial.